The present invention generally relates to taxi drive systems and more particularly, a movable bushing interface.
Existing designs for electric taxi systems (ETS) for aircraft may require a solid connection between the wheel rim or drive key and a drive element of an electric taxi actuator. This solid connection may adversely impact the structural integrity of the wheel rim. For example, during taxiing, the load of the aircraft may cause the wheel to ovalize on each revolution. Moreover, the loads exerted on the wheel may cause deflections of the wheel rim with respect to the axle. For example, weight on the axle during a turn may cause flexure of the wheel rim radially or axially from the drive element as the drive element may not want to flex with the load forces.
The combination of wheel ovalization and axial deflections caused by wheel side load conditions and axle bending may compromise the structural integrity in the interface between the ETS drive and the wheel. For example, point loading of forces on the drive element may lead to wear issues over time, expediting failure of the connection between the ETS and the wheel.
Referring to FIGS. 1A-1C, the effects of loads on a conventional wheel to wheel drive system connection 100 can be seen. FIG. 1A shows a wheel 110 connected to a drive ring 150 with minimal loads affecting the connection 100 which can be seen for example, during braking or at a standstill. FIG. 1B shows both wheel rim deflection and axle deflection of the wheel 110 from the drive ring 150. As shown in FIG. 1C, rim flexure may be approximately ±12.5 mm and axle flexure may be approximately ±8 mm. In a conventional wheel to wheel drive system connection 100, flexure in either direction may be a source of lost torque during taxi operations.
A wheel drive key (not shown) may sometimes be employed to connect wheel 110 to the drive ring 150. The wheel drive key's typical primary purpose is to drive the brake rotors (not shown) and provide the interface that decelerates the wheel 110 during aircraft braking. This same key may be used by the ETS system (not shown) as the input for the torque that is used to rotate the aircraft wheel 110 during electric taxi operations and ground maneuvers.
As can be seen, there is a need for an interface in the taxi drive system that can accommodate axial deflections and ovalization in the connection of the drive system to the wheel during operation.